Hydraulic tappet



March 5, 1963 J. w. HUMPHREYS HYDRAULIC TAPPET Filed May 7, 1962 3,079,903 HYDRAULIC TAPPET John W. Humphreys, Muskegon, Mich, assignor to Johnson Products, Inc., Muskegon, Mich, a corporation of Michigan Filed May 7, 1962, Ser. No. 192,722 4 Claims. (Cl. 123--90) This invention relates to externally fed hydraulic valve litters, and more particularly to valve lifters or tappets oriented substantially horizontally in the engine.

The development and adoption of horizontal engines has created the problem of hydraulic fluid draining from the horizontal tappets when the engine and tappets are not in operation. This causes extensive tappet noise when the engine is first started. Various devices and mechanisms are presently used to prevent drainage from the static horizontal tappet reservoir. These include special check valve mechanism (e.g. Howson 2,962,102), and special inserts having complex, tortuous, peripheral passageways (Papenguth 2,938,508). Although such devices operate quite satisfactorily, they introduce substantial fabrication and assembly complexities as well as substantial cost increases.

More specifically, the check valve mechanism necessarily comprises several parts including a moving valve member, a spring, and a specially machined valve housing. The insert device having a tortuous path running at least 360 around the periphery of the insert involves careful machining of the special casting or molding, or alternatively involves careful machining of the plunger exterior itself. In spite of these and other disadvantages of said devices, they have been adopted for lack of an inexpensive but yet effective means to accomplish the purpose.

It is therefore an object of this invention to provide a structure capable of eflectively preventing drainage from a horizontal tappet when the engine is not in operation, capable of freely passing hydraulic fluid through the tappet when the engine is in operation, and which is also extremely simple and inexpensive to manufacture and assemble into the tappet.

It is another object of this invention to provide a simple sheet metal, drainage-preventing insert having no moving parts, having no tortuous passageways to be machined therein, which is capable of being quickly and accurately inserted into a tappet plunger against an aligning shoulder, and the cost of which is only a fraction oi that of prior mechanisms to accomplish the purpose. The stamping insert utilizes the characteristics of the hydraulic fluid itself to forestall the drainage when the engine is not operating.

These and other objects will be apparent upon studying the following specification in conjunction with the drawings in which:

FIG. 1 is a sectional elevational View of the novel tappet assembly; and

FIG. 2 is a sectional view taken on plane ll-ll of the tappet illustrated in FIG. 1.

Basically, the invention comprises a horizontally operable hydraulic non-draining tappet including the usual elements of a valve tappet housing, plunger means operable in the housing, a pressure chamber formed between one end of the plunger means and the housing, a reservoir formed in the plunger, flow control means associated with the one end of the plunger providing one-way communication between said pressure chamber and said reservoir, and hydraulic fluid inlet means in the reservoir; and the improvement comprising a partition across the reservoir between the control means and the inlet means, and a valveless orifice in the partition having an axis coincident with an imaginary straight line extending through th partition. The orifice has a diameter large enough to inversely with the 3,9793% Patented Mar. 5, 1963 allow free flow of pressurized hydraulic fluid therethrough when the tappet and engine are in operation, and small enough to prevent unpressurized hydraulic fluid from flowing therethrough out of said reservoir when said tappet and engine are not in operation. It has been found that the diameter of the orifice is critical and can normally be no greater than about of an inch.

Referring now to FIG. 1, in the form of the invention there illustrated, the tappet 10 includes a cup-shaped cylindrical housing 12 having a cam-engaging surface 14 on one end and an opening 16 on the other end. Slidably interlitting within cylinder 12 is a plunger member 18 defining a fluid reservoir 20 therein. At one end of the plunger is a check valve means or flow control means 22. for allowing hydraulic fluid flow from the reservoir 2% to the pressure chamber 28, but preventing reverse flow therethrough. Control means 22 may be composed of conventional elements including plate valve 36, and spring 32.

A plunger return spring 33 may also be utilized in a conventional manner. In the opposite end of plunger 18 is a push rod seat 49 which may include a central passageway 42 and fluid flow valve 44 for lubricant flow through a push rod as taught e.g. in Bergmanu Patent 2,948,270.

Adjacent annular recess 46 in the outer periphery of cylinder 12 is provided an axial hydraulic fluid inlet 43 communicating with annular passageway 59 formed between cylinder l2 and plunger 18. Fluid flow through recess 46, passageway 48, andrecess 59, passes into the plunger interior at 52 through the axial passageway 54 in the plunger.

According to this invention, positioned between. the hydraulic fluid inlet means just described and the flow control means 22 is a partition 69, comprising a sheet material stamping, and preferably press-fitted against an annular aligning shoulder 62 in the plunger 13. In the partition is formed an orifice 64 having a diameter large enough to allow free flow of pressurized hydraulic fluid therethrough when the engine is in operation, but preventing reverse flow of the fluid out of the reservoir when the engine is not in operation. This orifice may be die-cut into the sheet metal baflle. The diameter of this orifice is critical, and must normally be smaller than about H of an inch. The orifice may be positioned any place on the partition 68-, as illustrated by the example holes shown in phantom at 7% and '72 in FIG. 2. The opening in the partition has a straight line axis coincident with an imaginary straight line drawn through the partition from the inlet side to the reservoir side. Conceivably, more than one such partition could be inserted as a multiple check, but only one has been found to be necessary. The size of the opening may vary generally in direct relationship with the surface tension and viscosity of the liquid and oil pressure applied.

In operation, pressurized hydraulic fluid is pumped through the inlet means, passes through the orifice 64 into the reservoir, and from thence through valve 39 to the pressure chamber 28.

When the engine is not operating, hydraulic fluid in the reservoir bulges into orifice 64 but does not flow therethrough due to the surface tension of the fluid. Neither can air enter into the reservoir, because of the liquid surface tension.

Such a device is a very simple and complete solution to the drainage problem. Indeed, its very simplicity is its chief virtue making it so valuable.

Various minor modifications of the device may occur to those in the art without departing from the principles taught upon studying this form of the invention. Such modifications are deemed part of this invention, which is to be limited only by the scope of the appended claims and the reasonable equivalents thereto.

I claim:

1. A horizontally operable hydraulic tappet comprising: a valve tappet housing; plunger means operable in said housing; a pressure chamber formed between the end of said plunger means and said housing; a reservoir formed in said plunger means; flow control means associated with the end of said plunger means providing one- Way communication between said pressure chamber and said reservoir; hydraulic fluid inlet means in said reservoir; a partition across said reservoir between said control means'and said inlet means; a valveless orifice in said baffle having an axis formed on an imaginary straight line extending through said partition; said orifice being capable of freely passing pressurized hydraulic fluid when said tappet is in operation; and said orifice having a diameter small enough to prevent unpressurized hydraulic fluid from flowing therethrough and out of said reservoir when said horizontal tappet is not in operation.

2. A horizontally operable hydraulic tappet comprising: a valve tappet housing; plunger means operable in said housing; a pressure chamber formed between the end of said plunger means and said housing; a reservoir formed in said plunger means; flow control means associated with the end of said plunger means providing oneway communication between said pressure chamber and said reservoir; hydraulic fiuid inlet means in said reservoir, a partition across said reservoir between said control means and said inlet means; a single valveless; orifice in said partition having an axis formed on an imaginary straight line extending through said partition; and said orifice having a diameter no larger than about of an inch to prevent unpressurized hydraulic fluid from flowing out of said reservoir when said horizontal tappet is not in operation, but large enough to allow free flow of pressurized hydraulic fluid therethrough when said tappet is in operation. I

3. A horizontally operable hydraulic tappet comprising: a valve tappet housing; said housing; a pressure chamber formed between the end of said plunger means and said housing; a reservoir formed in said plunger means; flow control means associated with the end of said plunger means providing oneway communication between said pressure chamber and said reservoir; hydraulic fluid inlet means in said reservoir; a stamped sheet metal partition press-fitted across said reservoir between said control means and said inlet means; a valveless orifice through said baifie having an saris coincident with a straight line extending through said partition; said orifice having a diameter large enough to allow free flow of hydraulic fluid therethrough when said tappet is in operation; and said orifice having a diameter small enough to prevent unpressurized hydraulic fluid from flowing therethrough and out of said reservoir when said horizontal tappet is not in operation.

4. A horizontally operable hydraulic tappet comprising: a valve tappet housing; plunger means operable in said housing; a pressure chamber formed between the end of said plunger means and said housing; a reservoir formed in said plunger means; flow control means associated with the end of said plunger means providing oneway communication between said pressure chamber and said reservoir; hydraulic fluid inlet means in said reservoir; at least one partition across said reservoir between said control means and said inlet means; a valveless orifice in said partition having an axis formed on an imaginary straight line extending through said partition; said orifice being capable of freely passing pressurized hydraulic fluid when said tappet is in operation; and said orifice having a diameter no greater than about of an inch to prevent unpressurized hydraulic fluid from flowing therethrough and out of said reservoir when said horizontal tappet is-not in operation.

No references cited.

plunger means operable in 

4. A HORIZONTALLY OPERABLE HYDRAULIC TAPPET COMPRISING: A VALVE TAPPET HOUSING; PLUNGER MEANS OPERABLE IN SAID HOUSING; A PRESSURE CHAMBER FORMED BETWEEN THE END OF SAID PLUNGER MEANS AND SAID HOUSING; A RESERVOIR FORMED IN SAID PLUNGER MEANS; FLOW CONTROL MEANS ASSOCIATED WITH THE END OF SAID PLUNGER MEANS PROVIDING ONEWAY COMMUNICATION BETWEEN SAID PRESSURE CHAMBER AND SAID RESERVOIR; HYDRAULIC FLUID INLET MEANS IN SAID RESERVOIR; AT LEAST ONE PARTITION ACROSS SAID RESERVOIR BETWEEN SAID CONTROL MEANS AND SAID INLET MEANS; A VALVELESS ORIFICE IN SAID PARTITION HAVING AN AXIS FORMED ON AN IMAGINARY STRAIGHT LINE EXTENDING THROUGH SAID PARTITION; SAID ORIFICE BEING CAPABLE OF FREELY PASSING PRESSURIZED HYDRAULIC FLUID WHEN SAID TAPPET IS IN OPERATION; AND SAID ORIFICE HAVING A DIAMETER NO GREATER THAN ABOUT 3/32 OF AN INCH TO PREVENT UNPRESSURIZED HYDRAULIC FLUID FROM FLOWING THERETHROUGH AND OUT OF SAID RESERVOIR WHEN SAID HORIZONTAL TAPPET IS NOT IN OPERATION. 